If you don't want to cut the body, it will be difficult due to the length of the rear body.
Start by preparing a wooden stand for it otherwhise, you might break the body once you will remove it.
Also, there is an annoying difference between the serie 1 ( yours) and 2 in the way the front part of the roof is glued on the chassis.
On the serie 2, it's only glued over the chassis
On the first serie, the front of the roof doen't include the lip and is just flat. It's married with the chassis with mastic
which will be destroyed at the removal and which you will have to artistically redo
Now the steps are
- remove rear bumper
- remove rear lights
- remove inox strips on the side of the roof
- remove internal panel holding the sun screens
- Drill the rivets holding the rear body ( 3 on the door side, 1 or 2 on the sills cover, some on the rear, to the boot)
- Use a heat gun on the steel part ( not the fiberglass ) on the side of the roof
After 3-5 minutes of heating, the glue should be removable and you can insert between the chassis and fiberglass a thin cutter.
Slowly you will undo the roof ( until you reach the front :-( )
The rear of the roof ( arround the boot) is just hold by this sticking white chewing gum ...
To put it back, for the boot surrounding, we now the reference of the correct product and for the roof, I'm successfully using windscreen glue.
You can buy it from renault, asking for the glue for espace body but then, you will discover that they just package and mutliply by 5 the price of a sikaflex glue that you can buy by yourself